The invention is particularly, but not exclusively, applicable to networks of intercommunicating microcomputers or microcomputers with other devices. It is particularly applicable to the communication between pairs of devices which transmit data packets consisting of a serial bit packet of a first format along a unidirectional communication line between the two devices and acknowledgement packets formed by a serial bit packet of a second format which is transmitted along a further unidirectional communication line between the two devices. Such communicating systems are described in the specifications of U.S. patent applications Ser. Nos. 553,027 (now 938,380) and 756,992. The disclosures of those two specifications are incorporated herein by cross-reference to those application numbers. In those communication systems, each pair of communicating devices are coupled by two separate unidirectional communication lines. One device which wishes to output data to the other sends a data packet along one communication line, the data packet having a fixed serial bit length commencing with a start bit and having a first format characteristic of a data packet. When that data packet is received by an inputting device, the inputting device causes an acknowledgement packet to be sent along the other of the pair of communicating lines between the devices. The acknowledgement packet also has a fixed serial bit length commencing with a start bit and a second format characteristic of an acknowledgement packet. Each data packet must be followed by an acknowledgement packet before a further data packet can be output.
The above mentioned specifications illustrate networks of interconnected microcomputers and other devices wherein the network has a format determined by the pairs of communicating lines between the devices in the network.
It is an object of the present invention to provide a digital signal switch which may be used for effecting a plurality of selectable interconnections between devices which communicate with each other by serial bit packets of two types. By use of such a digital signal switch, it is possible to provide different configurations of connections between the devices in the network.
The network structure can in this way be configured to perform a particular task. The switch can be used to construct reconfigurable networks of arbitrary size. In a preferred embodiment, the switch may be provided with a communication interface of the type described in European Published Specification No. 0141659 so that the configuration of the switch may be programmed by use of a microcomputer or other device connected to the interface.